qed: Don't allocate SBs using main PTT

Flows accessing registers require the flow to hold a PTT entry.
To protect 'major' load/unload flows a main_ptt is pre-allocated
to guarantee such flows wouldn't be blocked by PTT being
unavailable.

Status block initialization currently uses the main_ptt which
is incorrect, as this flow might run concurrently to others
[E.g., loading qedr while toggling qede]. That would have dire
effects as it means registers' access to device breaks and further
read/writes might access incorrect addresses.

Instead, when initializing status blocks acquire/release a PTT
as part of the flow.

Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>